One problem in assemblies of the type here involved is called "play " or looseness in the assembly. A small amount of axial play can and often does results in repetitive axial movement back and forth between the stops, which produces a hammering action and is very destructive.
The prior art which this invention replaces comprises a shouldered shaft and a component held against the shoulder by a nut screwed tight against the component. A keyway is cut in the threaded portion to receive a tab (extending radially inward) on a lock washer which has a peripheral tab adapted to be hammered against a flat on the nut. The lock washer is clamped between the nut and the component.
Such prior art device or method has a number of drawbacks, and this invention has these advantages over the conventional locking device:
1. Less expensive to make.
2. Reusable; when the conventional lock washer is removed, it is almost always so bent out of shape as to be useless, or the tab at the periphery breaks off.
3. The way some mechanics hammer the peripheral tab onto the nut, damage can and often does result to some part of the assembly.
4. Use of the conventional lock requires that the nut be turned to an arcuate position in which a flat rather than a corner is opposite the tab, which takes more time. In the invention lock means, the threaded plugs are screwed tight without regard to a final assembly indexing requirement.
5. The thread on the shaft in the conventional method is subject to damage, as by burring, etc. In a lock embodying the invention, the threaded portions are better shielded from damage.
6. In the conventional lock, if the peripheral tab bends away from the flat, or breaks off, the nut unscrews completely and the component comes off. In a lock device embodying this invention, if the threaded plugs back away from engagement, the assembly still does not come apart.
7. In a lock made according to this invention, the weight is more evenly distributed, so that there is less dynamic imbalance than in a conventional lock device. In very high speed applications, centrifugal imbalance can be a problem.